Apple as a source of dietary phytonutrients: an update on the potential health benefits of apple

1 Department of Industrial Plant Science and Technology, College of Agricultural, Life and Environmental Sciences, Chungbuk National University, Cheongju 361-763, Republic of Korea 2 Department of Food Science and Biotechnology, College of Agricultural, Life and Environmental Sciences, Chungbuk National University, Cheongju 361-763, Republic of Korea * Corresponding author: Keum-Il Jang: E-mail: jangki@chungbuk.ac.kr, Phone: +82-43-261-2569, Fax: +82-43-271-4412

: Recent studies on biological and pharmacological activities of apple and its products

Effect
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Hung et al., 2015
Apple oligogalactan potentiated the growth inhibitory effect of celecoxib in two human colon cancer cell lines (Caco-2 and HT-29 cell lines) and a CACC mouse model through influencing the expression and function of COX-2 and phosphorylation of MAPKs.

Qiao et al., 2015
A hospital-based case-control study suggested that the risk of colorectal cancer decreased with higher level of apple consumption, indicating the beneficial effect of apple on the risk of colorectal cancer.

Jedrychowski et al., 2010
In a case control study in Hawaii, it has been suggested that apple (odds ratio = 0.6, 95 % confidence intervals: 0.4-1.0) and onion (odds ratio = 0.5, 95 % confidence intervals: 0.3-0.9) intake was associated with a reduced risk of lung cancer in both males and females.
Le Marchand et al., 2000 Effect Summary Reference

Anti-obesity and anti-diabetic effects
Apple-derived pectin modulated gut microbiota, and alleviated HFD (high-fat diet)-induced body weight gain, fat mass development, dyslipidemia, hyperglycemia, hyperinsulinism, metabolic endotoxemia and systemic inflammation in obese rats.

Jiang et al., 2016
Young apple (30 days after blossoming) polyphenols inhibited the starch digestion by α-amylase. Sun et al., 2016 Methylglyoxal is a major precursor of advanced glycation end products linked to diabetes and its related complications. Phloretin from apples prevented methylglyoxal-induced cytotoxicity in human retinal epithelial cells via activation of the Nrf2 related defense pathway, indicating the potential role of phloretin as useful pharmaconutrient agent for complementary treatment/management of diabetes-related complications.

Sampath et al., 2016
Based on meta-analysis, it has been suggested that total apple product consumption, whole apples, apple sauce and apple juice were associated with higher diet qualities than those seen in non-consumers of the same food groups. In addition, total apple consumption and whole apple consumption were associated with a lower prevalence of obesity and a lower likelihood of obesity.

O'Neil et al., 2015
The metabolic disorders caused by high fat diet were thwarted by taking apple cider vinegar, which proves to have a satiating effect, antihyperlipidemic and hypoglycemic effects, and seems prevent the atherogenic risk. Bouderbala et al., 2016 The cloudy apple juice and apple peel extract of Egyptian Anna apple exhibited antihyperglycemic effects by reduction of the inflammatory response, mitigation of the oxidative stress, and normalization of the deranged lipid profile, suggesting that they might be useful therapeutic agents for treatment of deleterious complications of diabetes mellitus.

Fathy and Drees, 2016
The effect of apple on fasting blood sugar and plasma lipid levels in Type II diabetics' patients (42-70 years old) was investigated, and found that one medium size apple in diet of Type II diabetics reduces the fasting blood sugar and plasma lipid levels. Dange and Deshpande, 2013 According to Finnish study involving 10,000 adults, a reduced risk of Type II diabetes was associated with apple consumption.

Antiinflammation
Dried apple peel powder increases joint function and range of motion via the inhibition of COX-2 and lipoxygenase enzymes and reduction of ROS formation.

Espley et al., 2014
Apple polyphenols reduce inflammation response of the kidneys in unilateral ureteral obstruction rats via decreasing the expression and activity of COX-2, downregulating the transcription factor NK-κB and up-regulating the expression of Nrf2.

Lee et al., 2014
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Hepatoprotective
Apple polyphenol extract significantly enhanced the activities of superoxide dismutase and catalase and the rate of ATP synthesis and hydrolysis in the aluminum (Al)-treated rats, suggesting that apple polyphenol extract plays a role in reducing the toxic effects of Al in the liver of rats. Cheng et al., 2014 Cloudy apple juice significantly reduced the levels of hepatic ALT and SDH, and increased the pentoxyresorufin-Odepentylase (CYP2B biomarker) and NAD(P)H:quinone oxidoreductase-1 activities in hepatocarcinogenic Nnitrosodiethylamine (NDEA)-treated rats. These indicate that metabolic alterations induced by cloudy apple juice may protect against liver damage.

Antigenotoxicity
The treatment of apple juice resulted in decreasing the frequency micronucleated cells (erythrocytes and hepatocytes) in the cadmium-exposed rats. In addition, apple juice reduced the 8OHdG (8-hydroxylated guanine) levels and genetic damage in liver and peripheral blood cells.

Reduction of cardiotoxicity
Polyphenol-rich apple peel extract attenuates arsenic trioxide induced cardiotoxicity in H9c2 cells via alteration of the activity of lactate dehydrogenase, superoxide dismutase, catalase, glutathione, glutathione peroxidase, thioredoxin reductase, xanthine oxidase, calcium overload and caspase 3.
Higher apple intake was associated with lower risk of all-cause and cancer mortality in a cohort of women aged over 70 years, suggesting that an apple a day protects against death in elderly women, though reductions in the risk of cancer. Hodgson et al., 2016